1. Field of the Invention
This invention relates to a method of making an endless polymeric power transmission belt having a set of driving teeth on each of a pair of opposite surfaces thereof and to a belt made employing such method.
2. Prior Art Statement
So-called positive drive endless polymeric power transmission belts, wherein each belt has a set of driving teeth on each of a pair of opposite surfaces thereof, are well known in the art and many methods have been proposed for making such belts. However, the previously proposed methods have resulted in belts with various deficiencies which include belts having poorly defined driving teeth, belts having teeth with marginal load-carrying capabilities, and belts wherein certain ones of the teeth associated therewith have a pitch line which is poorly defined. In a typical belt of this latter type, the belt pitch line associated with the teeth on one of the opposite surfaces may be fairly accurately defined yet such pitch line once associated with the teeth (backside teeth) on the other of the pair of surfaces is erratic and poorly defined.
It is known in the art to provide a power transmission belt and method of making same wherein such belt has teeth on opposite surfaces thereof for the purpose of improving belt flexibility and as disclosed in U.S. Pat. No. 2,699,685, for example.
It is also known to provide a method of making a belt having driving teeth extending from only one of its surfaces and which employs a wound strand to define a so-called load-carrying band of the belt and as disclosed in U.S. Pat. No. 3,078,206.
It is also known to provide a method of making an endless power transmission belt having a set of driving teeth on each of a pair of opposite surfaces thereof wherein a single load-carrying cord is helically wound and employed as a load-carrying member for each set of driving teeth and as disclosed in U.S. Pat. Nos. 3,673,883, 3,897,291, and 4,042,443.
It is also known to provide a method of making a belt of the character mentioned in the next preceding paragraph by forming the belt in a similar manner as disclosed in the previously mentioned U.S. Pat. No. 3,078,206 and providing an added thickness of polymeric material on the belt portion opposite the toothed portion whereupon the added thickness of polymeric material is cut to define backside teeth therein.
It is an object of this invention to provide an improved method of making an improved endless polymeric power transmission belt having a set of driving teeth on each of a pair of opposite surfaces thereof.
It is another object of this invention to provide an improved belt of the character mentioned.
Other aspects, embodiments, objects, and advantages of this invention will become apparent from the following specification, claims, and drawings.